1. Field of the Invention
The present invention relates to an image-taking apparatus such as a digital camera or camera phone which is equipped with a release button and shoots a still image when the release button is pressed.
2. Description of the Related Art
Recently, instead of conventional film-based cameras, digital cameras which obtain image data of subjects focused on an image pickup element such as a CCD element as well as cell phones equipped with such a digital camera have come into wide use. Hereinafter, such cameras will be collectively or representatively referred to as digital cameras.
One of the problems with digital cameras is a time lag between a photographer's shooting action and actual shooting. Many of commercially available digital cameras have large time lags, often resulting in missing the right moment to take a photo.
To reduce such time lags, Japanese Patent Laid-Open No. 2-30633 and Japanese Patent Laid-Open No. 2-30634 disclose techniques for exposure control using results of metering for movie shooting by omitting metering for still-image shooting upon switching from movie shooting to still-image shooting.
However, in the case of movie shooting, light metering (hereafter referred to as metering) is performed on a frame-by-frame basis and the result of metering is used for exposure control of subsequent frames (few frames later). This requires quick metering, and metering is not performed over a wide range of field luminance suitable for still shooting. Recently, in particular, an image pickup element which has multiple photosensors with different areas per pixel and a wide dynamic range has made its debut. When shooting still images at correct exposure making-full use of an image pickup element with such a wide dynamic range, it is impracticable to apply results of metering for movie shooting to still-image shooting.
Thus, in order to perform proper metering for still-image shooting, a two-step release button which lends itself to a half press and full press is used with a sequence which consists of displaying a through image, i.e., moving-images for display, in normal state, performing detailed metering for still-image shooting in response to a half press, and shooting a still image in response to a full press.
In this case however, it takes time to complete metering for still-image shooting after a half press, presenting the problem of a time lag.